Compact balancer



c. s. WHITFIELD COMPACT BALANCER Jan. 2,1968

2 Sheets-Sheet 1 Filed June 25, 1965 FIGA INVENTOR CALVIN S.WHITFIELD ATTORNEYS Jan. 2, 1968 c s. WHITFYI ELD 3,361,155

COMPACT BALANCER 2 Sheets-Shem 2 FiledJune 25, 1965 INVENTOR CALVIN S.WH|TF|ELD FIG-8 v ATTORNEYS United States Patent 3,361,155 COMPACT BALANCER Calvin S. Whitfield, Atlanta, Ga, assignor of ten percent to Wilfred G. Caldwell, Arlington, Va. Filed June 25, 1965, Ser. No. 466,893 5 Claims. (Cl. 137-35523) ABSTRACT OF THE DISCLOSURE The invention relates to a pneumatic tool holder which supplies the air for operating the tool and also counterbalances the weight of the tool for automatic return. A frame is provided in which a drum is mounted for rotation. Spring means (negator) tension the drum against rotation and are adjustable to accommodate the different weights of different tools. The drum has a hollow interior and axle means fit into the interior. The air hose is wrapped around the drum and is reeled therefrom by drum rotation. The air supply is usually from an overhead stationary source and into the axle of the frame, via an internal air passageway in the drum to the interior end of the hose which is wrapped on the drum. In a preferred embodiment of the invention, the drum is tapered in order that the leverage arm changes to offset the increasing tension of the spring as the drum is unreeled.

The present invention relates to balancers in general and, more particularly, to compact balancers for use in lifting pneumatic tools, when they are not being used, to a safety level but mounting the tool for instant retrieval by the worker down to the work level.

In assembly plants, particularly in automotive assembly plants, the production areas usually exhibit a jungle of cables and hoses between about the three foot and six foot levels above the floor. This is because present day assembly tools, such as impact wrenches and the like, are pneumatically operated from overhead air hoses and are suspended from cables affixed to resiliently biased pulleys and carried by overhead racks. When not in use, the tools are carried upward to the safety level by the cable and pulleys and also the air hoses are wound up by overhead reels. Thus, for each pneumatic tool, one would encounter at least one air hose and one cable which clutter the Worker area when the tool is in use at the work level. Obviously, entanglements, kinks and wrap-arounds are encountered in this maze of cables and hoses, not only for single tools per se, but also among the tools.

The present invention eliminates these problems by eliminating all cables and associated pulleys or drums and by further confining each tool to a single pneumatic hose connection for both air supply and suspension in a reelable manner.

Preferably, this is achieved in a first embodiment of the invention, by providing a frame which can be mounted to the overhead and which carries therein a spool-type drum mounted for rotation relative thereto. An axle is provided to mount the drum in the frame and resilient means, preferably in the form of a negator spring, interconnects the drum and frame to provide relative adjustable tensioning therebetween.

A pneumatic hose of the length of, for example, four to six feet is wrapped around the drum and is adapted at its outer end for connection to a tool, such as an impact drill. Air pressure is delivered to the tool along an air passage established between the hose and an intake port accessible externally of the frame. The air passage includes a nipple or other suitable fitting formed on one end of the axle to which an air supply may be conveniently attached. Such an air supply may be delivered from the rafters or overhead in the building; but, in any event, it is disposed out of the working area.

The nipple is in communication with the bore which extends axially of the axle to a peripheral opening formed therein. A pair of sealing means, such as O-rings, provides an annular boundary on either side of the peripheral opening. With the axle in place in the drum, the 0- rings seat against its internal bore to provide an annular air chamber in communication with the axle peripheral opening. The passageway formed in the drum communicates with the axle bore and with a ridge on the drum spool outer periphery. A further nipple or connector is provided at the ridge opening for connection to the pneumatic hose which suspends the tool.

Lastly, guide means are provided for directing the hose from the drum and for precluding kinks and entanglements, in general.

In use, a particular tool is fitted to the reelable hose and the negator spring adjusted for proper suspension relative to the weight of such tool. Then the tool is simply pulled down to the working plane where it is instantly ready for pneumatic operation. When the operation is completed the tool is simply raised to the safety level by the pneumatic hose and is mounted in a safe but convenient location for further use.

A second or preferred embodiment of the invention employs a tapered drum with its leverage opposite to the differential tension of the negator spring to maintain substantially constantlifting pressure regardless of tool height or negator wind-up.

A unique air pressure communication structure enables the drum to turn without twisting the air supply hosing. The drum is hollowed or recessed on its small diameter side to accommodate the negator spring but the air pressure inlet side has an annular recess with a center shaft provided with an air passage bore.

A peripheral cover is arcuately depressed to define a hub adapted to fit or encompass the shaft in a bearinged manner. The air inlet assembly includes an outer and inner portion. The outer portion is screwed into the shaft bore and the inner portion is bearinged within the outer portion and protrudes beyond the peripheral cover plate to afford rigid connection to the supply hosing. Thus, in spite of drum rotation, the inlet (inner portion) remains stationary and the outer portion turns with the drum because of bearing between the cover hub and drum shaft. Air passage to the tool hose is otherwise similar to the structure of the first embodiment.

Accordingly, it is among the objects of the invention to provide a sturdy but noncomplex compact balancer capable of supplying pneumatic air pressure and suspending a pneumatic tool at different levels;

automatically adjusts the weight lifting force substantially constant by matching drum leverage to negator tension forces.

The foregoing will become more apparent from a reading of the following description of a preferred form of the invention when taken in the light of the accompanying drawings in which:

FIG. 1 is a view in side elevation of the balancer mounted to an overhead track;

FIG. 2 is a view in end elevation of the device of FIG. 1 with the hose in a somewhat retracted position;

FIG. 3 is a more detailed view in side elevation of the balancer per se;

FIG. 4 is an exploded assembly view of the device of the preceeding figures;

FIG. 5 is a view taken along the plane 55 to show the hose guiding means;

FIG. 6 is an exploded assembly view in cross section of a preferred embodiment of the invention, as seen along plane 6--6 of FIG. 7;

FIG. 7 is a view in side elevation of the balancer of FIG. 6, per se; and

FIG. 8 shows only the balancer of FIG. 7 in end elevation, without the hose.

Referring now to the drawings and particularly to FIG. 1 the balancer is generally indicated at 11 as being suspended from an overhead rack or track 13 by means of a conventional slider 15. The frame or cover 17 (FIG. 2) of the balancer 11 includes the upwardly protruding ears 19 which are adapted to be bolted to the slider 15 by bolts 21.

The tool carrying extensible hose 23 is shown extended in FIG. 1 with its operative end being fitted with a nipple 25 or other connecting means for attachment to a tool (not shown). The hose 23 is guided from reelable drum 27 by guiding means 29, better shown in FIG. 5.

Looking now at the exploded assembly view of FIG. 4 the drum 27 is shown without the hose 23 in order to reveal the air passage connections. As can be seen in the partly broken-away view, the dum 27 has a hollow interior into which an axle 31 is adapted to fit. The axle includes a hollow bore (not shown) extending from the nipple end 33 to the peripheral opening 35. The axle also includes the spaced apart pair of annular ridges 37 to the left of peripheral opening 35 and the further spaced apart pair of annular ridges 39 disposed to the right of peripheral opening 35. Conventional O-rings 41 and 43 respectively fit between ridges 37 and 39. The diameter of O-rings 41 and 43 is such as to fit snugly with the interior bore 47 of drum 27 thereby forming an airtight chamber from nipple 33 to connector 53. The outlet 35 is in communication with a passageway 51 formed in the drum core which may extend vertically or slightly arcuately about the drum core to terminate at connector 53 in a raised ridge 55 forming a portion of the external periphery of drum 27.

The inner end of hose 23 is connected to the nipple or connector 53 to extend the air passage from overhead supply (not shown) to the tool (not shown) adapted to be connected at end 25.

Kdjustable tensioning is provided through a conventional negator spring 61 which simply interconnects the drum 27 with the frame or cover 17. The negator spring is provided to permit adjustment of the tension for the particular tool employed with hose 23 in order that a balancing point may be reached.

The guide means 29 is best shown in FIG. 5 wherein four concave rollers 63, 65, 67 and 69 are shown mounted within the right angle face plate 71 of the guiding means 29 to alow the hose 23 to be readily drawn in any direction from the drum 27.

The guide means 29 is secured to the frame 17 by a bolt 81. Similarly, the axle is adapted to secure the drum 27 rotatably within the frame 17 through the provision of the nuts 83 and 85 adapted to fit the threaded ends of axle 31.

In the preferred embodiment, the drum is tapered from a larger diameter end to a smaller diameter end, e.g., from approximately 6% inches down to 5 /2 inches for a width of approximately 3 /2 inches and includes 3% turns or 4-track spiral recesses 103 for the hose 105. The drum 101 is at least partially hollow and includes centrally therein a protruding hollow shaft 107 of 1% inches diameter which constitutes the axle for the drum rotation. This shaft may be 1% inches in length and includes an annular recess 109 for a keeper 111 for holding the assembly together, i.e., the casing or frame 113 and drum 101. The outer casing or peripheral cover 115 includes a recessed semi-arcuately beveled portion 117 in the hub area, roughly 1 inch deep, in order that the shaft 107 will be accommodaed and the keeper recess 109 will extend to an accessible location from externally of the hub 119. The hub 119 includes a suitable bearing, as ball or like 121 which provides a bearing surface for the shaft or axle 107 of the drum 101 relative to the casing 113.

Air ingress is provided to the shaft 107 at this end by a fitting assembly 131 which includes an inner axle portion 133 forming the air passage entrance. It is supported by an outer fixed portion 135 within a needle bearing 137, press-fitted into the outer fixed portion 135 of the assembly 131. The inner portion 133 is externally threaded for connection to the air pressure source (not shown) or hosing, rotating within the needle bearing 121 so the supply hosing (not shown) does not tangle. The outer portion 135 is externally threaded for engagement with the interior of the drum shaft 107 to provide communication with an air passage formed in the drum.

An air seal is provided between the needle bearing surface of the outer portion and a reduced diameter shaft region 141 of the inner portion 133 which seats within the needle bearing 137.

The inner portion 133 extends slightly beyond the inner end of the outer portion 135 and includes an annular recess 143 for a keeper 145, to maintain the assembly together. The air pressure urges the inner assembly slightly outwardly of the outer assembly and a Tefion washer 147 (which requires no lubrication) is fitted between the keeper and the outer assembly 135 to provide a bearing surface at this point. It is this air pressure which also maintains a slight pressure and, thus, a separation between the interior abutment spacing flange (not shown) of the outer portion and the shoulder 151 of the bearing region 141 of the inner portion 133 so extensive surface rigid bearing requirements are eliminated.

The air passage is continued through the shaft 107 of the drum 101 which includes a bore 155 in communication with a radial passageway 157 which opens at either a circumferential ridge or outlet 161 (FIG. 7) formed on or internally of the drum periphery. It is at this position that the inner end of the hose 105 is connected to the air passageway 157 by a conventional fitting (generaly at 161). It should be pointed out that if the ridge 161 is located within the hollow of the drum 101, then a portion of the periphery of the largest track (103) must be relieved in order for the hose 105 to extend outwardly into the track; otherwise, the ridge may be located outwardly of the hollow, in the manner described in the previous embodiment.

The backside of the drum includes a recess 201 for a negator spring 203 which is fixed on its outer end (not shown) to the drum at notch 204 adapted to receive a turned-in end of the spring. The spring 203 receives, on its inner end 207, a shaft 209 suitably recessed at 211 to hold a right angle portion of the spring.

The cover plate 221 includes an external hub portion 223 adapted to receive the negator shaft 209. This hub portion 223 has openings 227 for a stop mechanism comprising an inwardly biased shaft 231 (by a spring, not shown) which is liftable against the inwardly biasing pressure to release the negator shaft 209 to permit winding or unwinding of the negator spring 203. The negator shaft includes the described diametrically opposite openings 227 for alignment with the locking pin 231 so that the latter may be locked (biased into the shaft) at the desired negator spring pressure to accommodate the particular tool suspended. A further keeper 251 on this shaft secures the assembly at groove 253 in connection with the screws 255 which maintain the cover 221 intact. Opening 261 permits any thin rod to be used to adjust tension when pin 231 is out of place.

The peripheral face cover 115 is fitted onto the shaft 107 with hearing 121 therebetween and secured thereto by washers 182, held in place by the keeper 111 that fits on the shaft 107. The other face cover 221 is bolted to the peripheral cover.

It may now be appreciated that one of the principal features of this embodiment is the tapered drum which maintains substantially constant tension pressure by virtue of the fact that as the negator spring tension is reduced, when the tool is raised toward its uppermost position, the leverage enabled by the tapered drum is minimized. However, the leverage increases as the tool is lowered to maintain this substantially constant tensioning pressure.

Also, it may be seen that a further feature resides in the provision of a hose retainer to maintain and guide the hoses properly in the spiral groove pathway and avoid entanglements and other foul-ups. An inner steel bushing 301 is rotatably fixed to a pair of cars 303 and 305, disposed in spaced-apart relation on the respective covers 115 and 221 to maintain light contact between the nylon or Teflon sleeve 310 and the hose. These ears contain slotted holes 313 for adjustment of the position of this roller 310.

While embodiments of the invention have been described, it should be pointed out that various modifications may be made without departing from the principles herein disclosed and, accordingly, it is intended that the invention be limited only by the scope of the appended claims.

What is claimed is:

1. A pneumatic tool holder comprising in combination a frame; a drum carried by the frame and mounted for rotation relative thereto; a spring means for tensioning the drum against rotation; said drum having a hollow interior; axle means fitting said interior; a hose Wrapped about the drum and adapted to be reeled therefrom by drum rotation; said drum being tapered and its surface includes spiral recesses for accommodating said hose; an air connection fitting carried by the axle and penetrating the frame; said axle and drum including an air passageway from said fitting to said hose at its inner end which is wrapped on the drum; and means setting the tension of the spring in accordance with the weight of a tool adapted to be connected to the other end of said hose for penumatic operation by air pressure applied to said fitting.

2. The apparatus of claim 1 wherein said frame includes a cover plate and a peripheral cover plate; said drum including a recess for said spring adapted to be closed by the cover plate; means for affixing an end of the spring to the drum; said cover plate including an outward- 1y extending hub; a spring shaft penetrating said hub for engagement with the other end of the spring whereby tensioning of the spring may be adjustably set by turn ing said shaft; and means for retaining the shaft fixed against rotation at the desired tensioning setting.

3. The combination of claim 1 wherein said frame includes oppositely spaced-apart ears on both sides of the drum and a rotatable shaft deployed across the drum and retained by said ears in contact with the hose to retain the latter on said drum.

4. The combination of claim 1 wherein said axle is a centrally disposed projection of the drum with a bore to comprise a portion of the air passageway and said frame is recessed so as to form a hub adapted to fit on the axle when the drum is assembled with the frame.

-5. The apparatus of claim 4 wherein said fitting comprises an outer portion adapted for engagement with the bore of the axle and an inner portion fitting within the outer portion and including an extension protruding beyond the outer portion for connection to the air source; bearing means disposed between the said portions whereby the outer portion rotates with the drum and the inner portion may remain stationary for connection to said air source; and means for retaining said portions in substantially said relation.

References Cited UNITED STATES PATENTS 1,206,563 11/1916 McConnell 137-25523 2,152,969 4/ 1939 Nash 242-107.4 2,219,201 10/1940 Smith 137-35523 2,342,020 2/ 1944 Stevens 242-107.4 2,519,064 8/1950 Palm 137-35519 2,568,929 9/1951 Palm 137-35523 2,609,231 9/1952 Crawford 137-35512 2,629,630 2/1953 Roark 137-35523 X M. CARY NELSON, Primary Examiner. S. SCOTT Examiner. 

